DISCOVER has covered scientists using DNA to investigate ivory smuggling in Africa and whether that’s endangered bluefin tuna in your sushi in New York City. Now an American team is using to that tactic to get on the trail of another questionable animal market, the sharks killed to make shark fin soup in Asia. The study appears in Endangered Species Research.

For the first time, scientists have used DNA from shark fins to determine where they came from. The researchers traced finds from the scalloped hammerhead shark species—collected at the world’s biggest fin market in Hong Kong—back to rare populations in the Atlantic and Indo-Pacific oceans [National Geographic News]. According to their analysis of the mitochondrial DNA, which they compared samples from live hammerhead population, 21 percent of the Hong Kong fins came from water off places like the United States, Belize, and Panama where the sharks are classified as endangered.

Shark fin soup is a Chinese delicacy that goes back centuries. Today it’s a form of conspicuous consumption.Says lead author Demian Chapman: “Shark fins are popular because serving fin soup at important events, such as weddings and banquets, is a sign of wealth and status…. Think of it as a Lexus in a bowl” [Discovery News]. It takes millions of sharks to satisfy demand, however, since only the fins are used (fisherman who harvest the fins usually throw the finless animals back into the ocean to die). Some scientists estimate that fishermen kill as many as 73 million sharks for their fins each year. Probably one to three million of those are hammerheads.

As shark numbers dwindle around the world, they may receive new protected status. Protection for hammerhead sharks will be considered at the Convention on International Trade in Endangered Species (CITES) at its March 2010 meeting in Qatar. The U.S. has proposed that CITES list the scalloped hammerhead and five other shark species [LiveScience].